


Magic Threads

by pinkstarpirate



Category: Haikyuu!!
Genre: M/M, Mermen, fantasyhaikyuuminiexchange, merfolk
Language: English
Status: Completed
Published: 2019-05-14
Updated: 2019-05-15
Packaged: 2020-03-05 09:39:13
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 7
Words: 8,944
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18826057
Author URL: https://archiveofourown.org/users/pinkstarpirate/pseuds/pinkstarpirate
Summary: From the time they were young, Kuroo and Kenma have been the closest of friends.  Now Kuroo wants to become a healer and go explore the wider world beyond the sea.  There is a thread of magic that runs through each of the merfolk and it is this magic thread that allows Kuroo to maintain a human appearance, but it also ties Kuroo to Kenma and reveals feelings that he didn't even realize he had.





	1. When We Were Young

**Author's Note:**

  * For [LittleKingCosplay](https://archiveofourown.org/users/LittleKingCosplay/gifts).

**Notes for the Chapter:**

> In this chapter Kuroo is 10 and Kenma is 9.

Tetsurou Kuroo’s small fingers grip the slippery rock on the outskirts of the cove. This particular rock is tall enough that a portion of it juts nearly three feet out of the water, despite it being high tide. The bulk of it below the water has been worn smooth by the constant beating of waves, but above it looks like most of the large rocks framing the beach in this area--dark grey and craggy, but also sturdy and bulky. Tetsurou sighs as a powerful wave threatens to pull him back out to the ocean depths with the exit of the tide; however, he is able to maintain purchase because it _is_ high tide and he is able to reach the jagged, natural hand holds that would be far too high for him any other time.

“What are you looking at?” a quiet voice asks behind him.

Tetsurou startles so hard that he nearly goes splashing back down under the water. Kenma allows himself to be dragged back with the retreating wave, but then he swims back to the rock and finds his own handhold.

“Kuro, what are you looking at?” Kenma repeats again, and his gills flick closed as Kenma switches from sea water to air.

“Nothing,” Tetsurou says as he cranes his neck to look over the rock again.

Kenma mimics Tetsurou’s posture and pulls himself high enough to see over the rock. There is a slight fear in the younger merman’s eyes as he releases his hold on the rock and slips soundlessly back into the water. Tetsurou can only see Kenma’s eyes lurking above the surface.

 _‘Humans. Dangerous,_ ’ Kenma says in a rush of quiet clicks just under the water.

“They can’t see us,” Tetsurou says with sigh.

 _‘Humans. Kuro. We go,’_ Kenma clicks again, this time a touch louder as he also uses a flourish of hand signals. The clicks aren’t as descriptive as spoken languages, of which both young Kenma and Tetsurou know several, but clicks are the mother tongue of the merfolk.

“I want to watch,” Tetsurou says with a huff, and then he does just that, he goes back to watching the small group of humans on the beach of the cove.

Kenma pokes his full head out of the water, fear still lingering in his eyes. “When did you get so brave, Kuro.”

“I’ve always been brave,” Tetsurou says with a soft laugh, though he knows it’s a lie. He used to be more shy than Kenma. He’s not sure why or when that changed, but there is a bravery in him now that wasn’t there when he and his father joined this particular pod of merfolk.

Kenma doesn’t join him back atop the rock, so Tetsurou flicks water at his friend with his tail, hoping that a little teasing will encourage his friend to change his mind. It does not. Kenma drops mostly beneath the surface of the water again, letting the ebb and flow of the tide move him, swimming closer again when the waves push him too far back towards sea.

“They’re playing a game,” Tetsurou says excitedly, watching attentively as an object flies over a rope back and forth several times.

The game sort of reminds Tetsurou of the game of keep-away merfolk do with prey fish when learning to hunt, but the thing the humans hit back and forth doesn’t move without assistance, unlike a fish that is always trying to swim away.

“Kuro, we need to go,” Kenma insists, pulling himself out of the water far enough to slap Tetsurou with his wide, spiny tail flutes.

“You’re the one who keeps making a ruckus,” Tetsurou whines, wanting to stay and watch this fascinating game the humans are playing.

He really does want to stay, but Tetsurou knows that he shouldn't. If his father finds out Tetsurou had been so close to humans, Tetsurou will definitely be disciplined. There are times and ages for those sorts of things, of course, but never as young as Tetsurou and Kenma are right now. Neither of them has found the thread of magic that ties them to their particular human forms. Obviously, that comes later.

Tetsurou finally slips down the rock and into the water with a only soft _schloop_ sound. He can be stealthy and silent when he wants, just like Kenma.

 _‘Ready. We go,’_ Tetsurou clicks to his friend under the water.

 _‘Kuro,’_ Kenma clicks back at him, shaking his head, then adds _, ‘Idiot,’_ as he darts away. It’s faster than Tetsurou has seen Kenma move in a long time.

Tetsurou engages his gills and pulls in a large gulp of water. When he compresses again, bubbles release from his nose and mouth and he follows Kenma back to the pod. For a moment, he feels a tingle in his fingertips as he remembers the game the humans were playing. It had seemed fun and he wants to try it someday. Tetsurou flexes his fingers as the tingling grows stronger. He wonders at the sensation. Later, when he describes it to his father and grandfather, his father tells him that this is the first stirrings of magic and it’s time for Tetsurou to start searching for the thread of magic that is all his own.


	2. Tetsurou’s Magic Thread

**Notes for the Chapter:**

> In this chapter Kuroo is almost 13 at the beginning. After the time jump Kuroo is 16 and Kenma is 15

Tetsurou’s father tells him that he is almost mature enough to find his destiny. Most of the merfolk aren’t as dramatic as his father is, but Tetsurou’s father and grandfather are both accustomed to the old ways. They are known as old souls, and Kenma often teases Tetsurou for being one of the old souls as well. For Tetsurou’s family, destiny isn’t dramatic, it’s inevitable. Both Tetsurou’s grandfather and father are keepers of history, though his father also works as a healer.

‘ _I be. Healer,’_ Tetsurou clicks to his father one morning as they hunt for fish. He is nearly thirteen and he loves the history that his grandfather tells and maintains, but is drawn much more to the healing magic his father does in his spare time.

His father leads Tetsurou to an empty beach cave hidden away from humans. They break the surface and dispel the water in their lungs. Tetsurou’s gills flutter closed as he takes a deep breath of air.

“Tetsurou, being a healer isn’t easy,” His father says as he pulls himself up onto the cool sand at the opening of the cave

“I know, but I want that,” Tetsurou says with a grin. His sharp teeth glint in the sunlight reflecting off the water.

Tetsurou’s father gives him a long, serious look. It almost becomes uncomfortable, but then his father speaks. “I’ve told you the history of humans, right?”

Tetsurou nods grimly. It is not a kind history.

“If you want to be a healer, I have something to ask of you,” his father says and pulls a stone out of pouch tied around his waist. “This is magic-imbued moonstone.”

Tetsurou gasps at this. He knows what this stone means, but he has never seen one in person, and he never imagined that his father possessed one.”

His father gives it to Tetsurou and it is smooth and warm in the palm of Tetsurou’s hand. “Tie your thread around it.”

How exactly do you tie a magic thread around a magic stone?

Tetsurou tips his hand to the left and then the right as the stone shifts and skitters over his palm. If Tetsurou can manage to actually tie his magic to this stone, his ability to maintain a human shape won’t be from sunset to sunset, but rather from full moon to full moon. The moonstone will connect him to the water and its magic without being near the sea, and as long as Tetsurou lets it naturally recharge in the moonlight or in the sea once a month, he will be able to maintain a human form.

“I need you to do this, Tetsurou,” his father says as he watches Tetsurou trying to slip magic around the stone. “Healing magic can only do so much and there is only so much magic to be had. Humans used to know so much less than we did about healing, but now they know so much more. We need to gain that knowledge, so you’d still be a historian in a way, but a historian of healing.”

Tetsurou looks up at his father in stunned silence and wonders at the implications of the older merman’s plan. “You want me to live among the humans?” Tetsurou finally asks. “And you want me to learn how to heal like the humans do?”

His father gives Tetsurou a sad smile. “I do. I know you’ve always been fascinated by them. And there are many of us who live among them. However, neither your grandfather nor I will be able to join you. As the pod’s historians, we cannot risk the loss of that tradition.

Tetsurou knows he has three cousins being trained by his father and grandfather to be the pod’s next generation of historians. He also knows that his grandfather had hoped Tetsurou would join them when he came of age.

Tetsurou realizes that if he accepts this as his destiny, it will be a lonely journey. He also knows deep in his heart, where a flourish of magic stirs, that this is the correct path for him. He looks up at his father as a single tear runs down the elder Kuroo's cheek, and with that, the thread of Tetsurou’s magic ties tightly around the moonstone.

“I’ll make you proud,” Tetsurou tells his father.

“You already have,” Tetsurou’s father says as he ruffles the messy cut of Tetsurou’s hair.

 

* * *

 

Almost three years later, Tetsurou stands in a nearly empty cove. His father is lying at the water’s edge, tail fidgeting nervously. His grandfather is further out in the sea, but still visible, having already said his goodbyes to his grandson.

“Every month,” the elder Kuroo warns his son, “At the time of the full moon. And you can’t be drawing on the power of the stone when it recharges. It has to be in the light of the full moon or in the salt waters of the sea.”

“I know, I know,” Tetsurou says as he stretches out his legs. He has been practicing this as much as he can with Kenma, but it still feels slightly awkward, especially with the clothing that he has to wear to fit in with the humans.

Tetsurou doesn’t want to leave yet, even though his guide is impatiently tapping a foot on the sand. Kenma is supposed to come and see him off, but Tetsurou’s childhood friend, his _best_ friend, isn’t here.

“Just a few more minutes,” Tetsurou says to the guide, who huffs and starts making his way up the beach. It is implied that Tetsurou will catch up.

Tetsurou says a final goodbye to his father and is about to leave when he sees a splash in the water out near his grandfather. The spray of water is frantic and large and Tetsurou can hear his grandfather clicking at whoever it is, admonishing the merfolk rushing toward shore.

“Kuro, wait!” Tetsurou hears as Kenma flails up onto the beach.

The smaller merman flips on the sand and he grabs something from a pouch. He holds it tightly in his fist and mumbles words and flips his tail until it slowly melts, thanks to the magic being called upon, into two human legs. Also gone are Kenma’s sharp teeth, gills, and slitted pupils. Kenma stands before Tetsurou as a human, with a moonstone in his hand, and not a stitch of clothing on his body.

“I was finally able to tie the thread. I didn’t...I didn’t think I was going to be able to do it,” He says quietly.

And so, two young men, fourteen and fifteen, stand in their human forms, holding similar moonstones, are ready to take on the human world. Tetsurou smiles and embraces his friend. Kenma pulls back and reaches into a woven kelp bag. The clothing inside is wet and worn, but Tetsurou knows they’ll get something better when they get to wherever they are staying. Tetsurou’s father waves a hand and Tetsurou recognizes the thread of his father’s magic as the water disappears from the clothing and is returned to the sea.

“Good luck, boys. See you at the full moon,” the older Kuroo says as Kenma dresses in his newly dried clothes. The two boys wave goodbye to Tetsurou’s father and hurry to catch up with their guide.


	3. New Friends Appear

**Notes for the Chapter:**

> In this chapter Kenma and Akaashi are 15, and Bokuto and Kuroo are 16 and first years. Akaashi is still in middle school and Kenma isn't attending school yet.

Kenma splays himself across Tetsurou’s bed in their shared bedroom. He is playing one of the handheld games that their guide Suzuki allowed them to borrow. And by borrow, it means that it really hasn’t left Kenma’s hands since he got it. To say Kenma is enamored with the thing is the biggest understatement of Tetsurou’s life. It has been three months since arriving in the human city called Tokyo. Tetsurou feels ready for his journey of knowledge to become a human healer, or a doctor as it is called here. Kenma is still out of sorts in this new world, and has decided to stay behind as Tetsurou begins his education. Tetsurou isn’t sure if it’s really that, or that Kenma just wants to stay inside and play games all day.

Education in the human world is an entirely different ordeal than it is in the merfolk one. Where merfolk treat it more as a mentorship and work one-on-one with their young, or in very small groups, humans come together in buildings called schools, in large groups of younger humans. It’s different, but it also fascinates Tetsurou.

Games helped Kenma learn written communication, but Tetsurou still struggles with it some. However, he is making strides. Tetsurou is the son and grandson of oral historians. He has an amazing memory that allows him to lock away almost any information he hears. Tetsurou spends hours sitting next to Kenma trying to read the books from his classes. He is most interested in the science books and all their alchemy and rules. It is fascinating to learn.

Every few minutes Tetsurou tips the book toward Kenma and points at one of the words. Sometimes it is because Tetsurou genuinely doesn’t know it, others it’s just to see if Kenma does. Kenma always knows the words.

“You really should be going to school with me,” Tetsurou says.

“Why? To learn medicine and play that balled game you do?” Kenma says, squinting at the screen of the handheld game and sighing as he has to restart a level.

“Volleyball. It’s called volleyball. And yes, you should come and play it with me. You’d like it.” Tetsurou peeks out of the corner of his eye to gauge Kenma’s reaction. He watches as Kenma rolls his eyes hard at the suggestion.

“I wouldn’t like it. I miss my tail.  I don’t like running, some days I don’t even like walking, I definitely hate jumping, and the thought of hitting a ball sounds stupid.”

Tetsurou huffs, frustrated that Kenma won’t even give it a chance. “Well, will you at least come and watch the scrimmage we’re having this Saturday? We’re playing one of Tokyo’s top teams.”

“And that is supposed to entice me?” Kenma asks, sliding down from his seated position until he successfully slinks onto his back on the mattress.

“Yes, because you’ll be able to see the strategy of it, and I know you love that kind of thing,” Tetsurou tries, hopeful that Kenma’s love of strategy will perk his interest.

“How much strategy actually goes into a stupid game like volleyball?” Kenma asks as he pauses the game mid-level and looks up at where Kuroo is sitting next to him.

Tetsusurou grins mischievously as he realizes that he finally piqued Kenma’s interest. Kenma doesn’t pause his game for just anything, after all. It is absolutely time for Tetsurou’s piece de resistance…

“You can bring your game handheld with you. If it’s boring, you don’t have to watch.”

With a loud, defeated exhale, Kenma finally capitulates to Tetsurou’s request. “Fine,” he says as he unpauses his game.

 

* * *

 

 

Tetsurou is in the locker room with the other first-year players--Kai and Yaku. Yaku and he share a rivalry that has annoyed their teammates and coaches on many occasions, but today the two of them are generously trying to set it aside in order to win this game against a tough opponent. Tetsurou only has experience playing in one other scrimmage, so he is looking forward to getting on the court and letting his human body fly high above the net.

“Warm-ups!” one of the third-years yell into the locker room.  The three first-year players and a handful of their older teammates head out to the court.

There is quite the crowd present for an early-season scrimmage. Up in the stands there is a cheering section for the other team who are all holding up signs that say the players’ names. Tetsurou squints, trying to read them, but kanji and names still slightly confuse him.

“That one right there is my name!” an excited player from the other team tells him as they meet on the outside edge of the court. “Bokuto Koutarou! Nice to meet you.”

Tetsurou watches as, just for a moment, Bokuto’s eyes flash from normal golden-brown, to a piercing golden-yellow with the long slit pupils that most merfolk are known to have.

“I wanted to welcome you personally,” Bokuto continues. “When I heard that Nekoma got a talented new wing-spiker, I knew I had to meet ya. I want to know if you can handle my powerful spikes!” And as Bokuto says this, he rubs his right shoulder and arm and rotates it slowly as if warming up. The other presumed merfolk is throwing down a challenge. Tetsurou isn’t sure what to say.

At the same time, up in the stands, Kenma, who is dressed in a too-large hoodie and jeans, sits in the corner and watches as some guy with spiky black and white hair gets up in Kuroo’s face. It makes Kenma nervous to watch, because he is always worried that he or Kuroo might accidentally give away their true identities as magical, shapeshifting merfolk.

“Don’t worry,” a silky, low voice says as someone sits down right next to Kenma, “He’s harmless.”

Kenma’s head jerks up as he sees the other boy that has seated himself on the bench inches from Kenma. He is pretty and young, probably the same age as Kenma. As Kenma continues to scrutinize the other boy, he scans down to see that this person’s hand is palm up, and in the center of that palm is a beautiful stone that is worn smooth. It is a moonstone, just like the ones that Kuroo and Kenma use. Kenma can see the magic glinting in it, like he can with all moonstones.

“You...you’re like me, aren’t you?”

The other boy gives a soft chuckle as he nods. “Mmhmm, and so is my brash friend who is harassing your friend. You’ll have to excuse him. Bokuto is always excited to meet those like us. That, and he loves volleyball.”

 _What is it about this game that draws our kind?_ Kenma wonders as he sees Kuroo and the other merman named Bokuto laughing and then being shooed to their respective sides of the court by coaches.

With a slight, but warm smile, the boy next to Kenma says, “And my name is Akaashi Keiji, what’s yours?”

 


	4. Making Friends and Magic Threads

After the game finishes, and after taking a quick shower, Tetsurou runs to find Kenma.  Tetsurou saw him during the game, sitting on a bleacher next to a random person. Kenma making friends?  Well, Tetsurou supposes, stranger things have happened. Stranger things, like how they aren’t the only two young merfolk in Tokyo.

“Kenma!” Tetsurou says loudly as he bounds up into the stands, right to where his friend had been sitting.  The spot is empty now, so Tetsurou scans the rest of the gym, hoping to find him. A door at the very top of the stands swings open, and there is Kenma with the same person he sat with during the entire game, but also Bokuto, who is grinning like an idiot as he waves Tetsurou up.  

Tetsurou is pretty sure that door leads to somewhere most students aren’t allowed to go, but he takes the stairs two at a time, despite his fatigue from the hard-fought volleyball game, and reaches them within seconds.  He goes through the door and the dark-haired young man quietly slips it closed behind them.

“Man-oh-man,” Bokuto says in an almost too-loud whisper, “When our guide said there was some other merfolk our age in Tokyo, I was psyched to meet ya!  Most human-changed merfolk are adults, but we decided to come here a few years ago when Akaashi learned how to tie his magic string to his moonstone.”

The boy named Akaashi, who looks to be about fifteen, the same age as Kenma, sighs heavily as he corrects Bokuto.  “Bokuto-san, if you remember correctly, I was waiting on you. I tied my string several full moons before you.”

Bokuto’s brows scrunch together as he scrutinizes what Akaashi says, but just as quickly his eyes light up as he points at Akaashi as practically shouts, “That’s right ‘Kaashi!  You were way younger than me when you tied the string!” Bokuto turns to Tetsurou and Kenma and says, “Holy crap, you guys, ‘Kaashi here is great with magic. He knows lots and lots of it!”

Tetsurou glances from Bokuto to Kenma, who is standing between the other two human-merfolk.  Kenma looks pretty uncomfortable, shifting from one foot to the other, but he doesn’t slip away, as he is known to do during most conversations when their guide or some of the other adult merfolk try to talk with him.  However, it is clear that being next to the boisterous Bokuto isn’t working for him.

“Kuro,” Kenma says quietly, and reaches for Tetsurou’s hand.  It is something Kenma does whenever he feels overwhelmed. Tetsurou takes his friend’s hand and pulls him over to his side, letting his fingers slide securely around Kenma’s fingers.

Bokuto’s brows raise as he gets quiet and then he grins.  “Oh,” is all he says.

“We didn’t know that you two were promised,” Akaashi adds, looking sheepish as he glances as Bokuto.  “I assure there won’t be problems from us, because we are promised to each other too.”

 _Promised?_  Tetsurou thinks, trying to understand what this other boy means.

Then Bokuto gives a sharp click, one that doesn’t sound quite right outside of water, but it is definitely of the merfolk.  This particular click is not in regular usage in Tetsurou’s or Kenma’s pod though, so the translation isn’t perfect. Akaashi and Bokuto are obviously from another pod, but Tetsurou vaguely recognizes the click to mean ‘promised together.’  Some of the older merfolk in Tetsurou’s pod use something quite similar in reference to their mates.

Mates.  Tetsurou gives Kenma a look and Kenma gives the same confused and embarrassed look back.

“I mean, we haven’t like, ya know, yet.  We’re still too young for it to be official.  But someday. That’s why we’re promised,” Bokuto says with a fond smile as he looks at his friend...his promised?  Tetsurou knows it isn’t unusual for pairs to be made very young in some pods. Usually when two merfolk are found to share great fondness for each other, or when their magic becomes intertwined.

“We’re not,” Kenma says in a rush, trying to correct Akaashi.  “Kuro is a friend. We’re not promised.”

Akaashi gives Tetsurou and Kenma a curious look, and Tetsurou knows why.  The place where Kenma’s hand meets his own, the flicker of Kenma’s magic wraps around Tetsurou’s wrist as it coaxes Tetsurou’s magic to it and twines them into a single thread.

“Well, something tells me that you probably will be,” Bokuto says with a wink as he elbows Tetsurou in the side.  

Kenma mumbles a quiet, “Gross,” before letting go of Tetsurou’s hand, pulling the threads of their magic apart.  “He’s my childhood friend.”

However, Tetsurou sees the hot, embarrassed flush that goes from Kenma’s collarbone to the tips of his ears.  Kenma may be shy, but surprisingly, he isn’t usually embarrassed easily. Not only that, but Tetsurou can feel the ends of Kenma’s magic stretching and reaching for his, and without thought, Tetsurou’s magic heeds the call and bridges the distance until the two magics are woven into single thread once more.

“This is...it’s new,” Tetsurou says as he revels in the warmth of Kenma’s magic touching him.

Kenma doesn’t say anything, he just looks down at his feet.  Tetsurou feels Kenma’s magic hesitantly caress his own as it wraps around and strengthens the already bonded thread.  This is something personal between them, it is something _intimate._

Tetsurou is too stunned to say a word, and Akaashi and Bokuto are also quiet.  They can likely see and feel the magic weaving happening near them. Kenma finally breaks the silence as he says, “Kuro, I want to go home now,” as he walks away from the group, escaping away from their conversation like he does with most other conversations he feels trapped in. Kenma stops by a window further down the empty hallway and watches whatever is going on at street level and ignores the other three boys.

“I’m sorry about that,” Tetsurou says, and his voice sounds like he is almost out of breath, like the wind has been knocked from his lungs.

“Don’t worry, it’s normal.  You can’t control it, at least not at first,” Akaashi says quietly.  “It was the same for us. Well, maybe not quite the same. We were young enough to not be…” and Akaashi pauses as if he knows that continuing will make this more awkward for Tetsurou rather than less.  

Unfortunately, Bokuto has no shame as he finishes Akaashi’s thought.  “He means we were never embarrassed about it. Our magic was always woven together.  It’s just natural with those who are promised. So don’t be embarrassed!” Bokuto says with a hearty laugh.

“They’re not promised, Bokuto-san,” Akaashi reminds his partner.  “They’re friends. This is obviously a change for them.”

Tetsurou stops listening to Bokuto and Akaashi as he looks down the hallway and sees Kenma staring back at him.  He also feels the flicker of Kenma’s magic, reaching for him despite the long physical distance between them. Tetsurou sends a thread of magic to meet it and sighs when their magic twines again.

What will the two of them do now?


	5. A Trip Home

“I don’t want to talk about it, Kuro,” Kenma says as he keeps his eyes glued to his handheld game.  

The two of them sit in their normal spot atop Tetsurou’s bed.  Tetsurou might have thought Kenma was really trying to ignore him if not for the thread of Kenma’s magic twining and weaving, almost unbreakably at this point, with Tetsurou’s magic.  

“I am not letting you ignore this,” Tetsurou says as he makes a grab for the game.  Kenma turns away lightning quick and actually hisses at Kuroo, warning him not to try that again.

Tetsurou huffs and crosses his arms across his chest.  “Fine. You win. We’ll pretend that your magic and my magic aren’t doing... _things_.”

“Stop being an idoit,” Kenma says and he drops the game onto the bed and pulls his knees to his chest.  “I’m not ready to be promised, Kuro. And I’m…”

Tetsurou feels a jolt of magic run up the thread that connects them.  It is a very strange sensation. Then, without warning, Tetsurou sits up, spine straight, as a tiny bit Kenma’s magic reaches inside of him.  “What are you doing!?!” Tetsurou shouts frantically as he tries to push the magic out. “Kenma, stop!”

“I’m not doing it.  I’m not!” Kenma says, but he looks confused and scared.

The magic continues to try and push into Tetsurou, little by little.  And as if this creates a call-and-response, Tetsurou’s magic surges forward, and to his horror, it pushes into Kenma.

“Kuro,” Kenma whines, but almost seems resigned to this strange thing their magic is doing.

Then the magic does something absolutely bizarre, something Tetsurou didn’t think was possible--it blends.  What is Kuroo’s magic softens and melts and phases into the warm, rhythmic pulses of what is Kenma’s magic. And soon, there is no Kenma’s magic or Kuroo’s magic, there is only _their_ magic.

The two of them run as quickly as they can to their guide.  

“What in the hell?” the older merfolk says as Tetsurou and Kenma push abruptly into Suzuki’s office where he is trying to get some work done.  And then before the frantic pair of teens can say anything else, Suzuki sees it. “Oh,” he says softly, almost in awe.

“What is this?” Tetsurou says with no little amount of panic in his voice.

Suzuki motions for the two of them to sit down, trying to get the frightened teens to calm down.  Tetsurou plops down in one chair and Kenma sits cautiously in the other, and both of them try to keep as much space as possible between themselves.

“There is no Japanese word to describe it,” Suzuki says bluntly and then makes a very odd-sounding click, one that Tetsurou thinks might mean ‘shared’ but it obviously means more than just shared.

“How can we be sharing one magic?” Kenma asks, looking like he is on the verge of tears as pulls himself into a small ball on the chair where he is seated.

“It’s rare, but not unheard of.  Most of the time when one magic joins with another magic, the threads just twine and become a single thread.  That thread can always be pulled apart if the two merfolk desire. Sometimes though, magic spun together is highly compatible.  It loses its ability to be separate and it literally becomes one magic,” Suzuki tells them.

Tetsurou’s heart beats wildly as he feels this new magic, this ‘one magic,’ as it flows in his veins, but also flows in Kenma’s veins.

“Can it be undone?” Kenma asks in a scratchy, worried voice.

“I’ve never known it to be possible, but I don’t think that those who have shared magic ever wanted to separate themselves from each other.”  Suzuki looks at Tetsurou and then at Kenma with a severe expression. “The full moon is this weekend. I think it might be best if you head back early and see the elders about this.  I’ll tell your school that you are ill, Tetsurou.”

Home.  Maybe the elders have the answer.  Maybe his grandfather has knowledge from the histories that he keeps.  Maybe his father and the other healers have magic that can undo it.

 

* * *

 

 

When the two of them arrive home it is already halfway through the night.  It feels weird to have a tail again after so long. The last few months, Tetsurou only spent a night, less than twelve hours, in his merfolk form before returning to his human form.  Not only that, but he just lounged in a cove with his father, grandfather, and Kenma and didn’t swim much at all. The lack of use causes Kuroo to be graceless as he darts through the water, running into things every now and again because he doesn’t turn quickly enough or sharply enough.

Just before the two of them get to the pod, Kenma stops.  He floats next to a large reef of coral. Kenma doesn’t say anything and doesn’t make a single click.  He looks at his hand and then at Tetsurou. There is something incredibly hopeful in how Kenma swims forward and takes one of Tetsurou’s hands in his.

‘ _Not promised_ ,’ Kenma clicks. There is a long pause as their shared magic slowly engulfs both Kenma and Tetsurou’s hands.   _‘Someday. Maybe,’_

‘ _Someday. Maybe_ ,’ Tetsurou clicks back, unable to look away at the bashful way Kenma is acting.

And that is how Tetsurou’s father finds them--holding hands, magic as one, Kenma flushed warmly despite the cold of the ocean waters.

‘ _Father!’_ Tetsurou expresses in an excited click.

The elder Kuroo cautiously swims around the pair of young mermen, examining the magic from all angles before clicking the same unknown word that Suzuki used.  ‘ _One magic.’_

 _‘Surface_ ,’ Tetsurou clicks back to his own father as he gestures toward the ocean’s surface.  There are only so many things he can say in clicks, and this conversation requires nuance, things that Tetsurou desperately wants to convey.

‘ _Let’s go_ ,’ the elder Kuroo clicks as he swims up toward the steady rhythm of waves.

**Notes for the Chapter:**

> The last two chapters aren't quite ready yet. I'm hoping to have them finished and edited in the the next day or so.


	6. A Decision

The three mermen break the surface and find that the water is electric with energy.  Choppy waves make it hard to stay in proximity of each other to speak. Tetsurou glances up at the sky and realizes there aren’t any stars showing through the heavy cover of dark clouds. It is a prelude to an ocean swell.

Tetsurou’s father closes his eyes and extends his magic along the waves, soothing them. The push and pull of the water lessens as he creates a small bubble where the kinetic energy of the ocean has to go around rather than through. Tetsurou likes that he understands the physics behind this, one of the many things that he has learned in his human school.

“What happened?” Kuroo’s father asks when it is quiet and calm enough in their small patch of water.

“I don’t know,” Tetsurou says, making the shared magic more visible so his father can see how it connects between himself and Kenma. “We were just sitting together like we always do and the magic seemed to have a mind of its own.”

Tetsurou’s father considers this for a moment before sending a tendril of his own magic to touch the blended magic of his son and his friend. “It’s new, but surprisingly stable. Was your magic twining together before it became one?”

“Yes,” Kenma says quietly. “For a couple a days, I guess.”

Tetsurou’s father looks shocked and he clicks a sound that signals astonishment. “Days?” he asks when he finally finds words. “Only days? Not weeks or months? I suppose that’s true, because I didn’t sense your magic joining together at the last full moon, but that is unusually fast.”

Tetsurou has little experience with magic that twines. He remembers years ago when his mother and father would spin their magic together so they could work bigger magics with their combined powers. There had been a sense that the combination of his parents’ magic was something special, but he had been so young then that the memory is fragmented and vague. And it brings forth other memories as well, such as his mother’s death, and how he and his father had to return to his father’s childhood pod in the aftermath of grief and mourning.

“Is there a way to change it back?” Tetsurou asks, but the longer the magic is blended, the less he actually wants to convert it back to individual threads. Still, he wants to know if it can be reversed.

His father considers this and once again sends a thread of his own magic out to brush against Tetsurou’s magic. The sensation is calming as he feels the strong pull of his father’s power. With magic like that, Tetsurou knows his father could be more than just a historian and healer, but he also realizes that his father is content with his simple life helping others and telling stories. Perhaps the elder Kuroo worked to become stronger in order to be a better healer, so no one else had to lose their partner like Tetsurou’s father had lost his.

After exploring their magic, Tetsurou’s father gives them a solemn look and asks, “I can do it, but do you really want to separate your magic back to how it originally was?”

Tetsurou rushes out the word, “No,” as Kenma mumbles the word, “Yes.”

The two of them share a look, and there's a sadness in it that roots deeply in Tetsurou’s heart. He knows that whatever he may desire, the thing he wants most is Kenma’s happiness. “Yes,” he says, just as Kenma also changes his mind and says, “No.”

“Perhaps the two of you should talk before going any further,” Tetsurou’s father suggests. “I’ll give you some privacy. The wave spell should last another hour, so take your time. Call to me when you’ve made a decision.”

With that, the elder Kuroo dives down into the ocean and the two young mermen are left alone.

“What do you really want to do, Kenma?” Tetsurou gently asks his friend.

Kenma can’t seem to meet his eyes. “I’m not ready to be promised, Kuro” Kenma finally says. “I didn’t mind when our magics only twined, but this seems to be so much more…” and his voice trails off.

It does feel like there is something uniquely intimate to this sharing magic. It is almost like Tetsurou can feel his best friend’s worries, and how the situation frightens Kenma. He can also feel frustration edged along the worry, but there is also a deep, contented longing present in their shared emotions.

“Did you mean it?” Tetsurou asks, and when Kenma gives him a confused look, Tetsurou clarifies by adding, “When you said that you might want to be my promised someday?”

Kenma lets himself bob below the surface just enough that all Tetsurou can see is Kenma’s eyes and the top of his head. Kenma stays like that for a long moment before coming back up, cheeks hotly flushed as he nods. “Would you want that, too?” he asks.

Yes! Tetsurou’s inner voice silently shouts inside his mind. He does his best to calm that rash impulse when Kenma’s eyes go wide.

“You said yes,” Kenma says, still shocked. “You said yes, but you didn’t actually say anything.”

Tetsurou is too stunned to respond. Kenma heard him? Kenma heard his thoughts? Tetsurou, once a tiny, painfully shy merfolk, befriended Kenma when he was barely five.  It was right after the death of Tetsurou's mother, at a time when Tetsurou's heart was filled with grief. The bond of their friendship grew strong through the years, and though the two of them could long deduce what the other was thinking with extraordinary accuracy, this is the first time that one of them literally knows what the other is thinking.

“This is weird,” Kuroo says, stating the obvious.

“You think?” Kenma responds in that ‘you are such an idiot, Kuro’ tone he often reserves for his friend.

But just beyond those words, Tetsurou hears...maybe feels, a voice rippling through his mind. _I’m scared, Kuro,_ it says.

“Please don’t be,” Tetsurou says as he pushes through the water with one gentle stroke of his tail. He stops inches away from Kenma. “This is new, but I don’t think it’s wrong.”

Their magic vibrates in response to their nearness, and Kenma looks up at Tetsurou. “This is a lot, Kuro,” he says, but he also leans in and lies his head against Tetsurou’s chest. The two of them embrace and feel the magic pulse through them. “Does this mean that we’re promised?” Kenma says aloud, but an afterthought rushes into Tetsurou’s mind as he hears Kenma also silently say, _I’m not ready to be promised._

“I think,” Tetsurou begins, choosing his words carefully, “That neither of us are ready to be officially promised. But,” and he draws in a deep breath before continuing, “I think that someday I might.”

 _Someday I might, too,_ says Kenma’s inner voice. It is still odd to have words appear in his head, but Tetsurou chuckles as he hugs his friend tighter. Maybe Tetsurou’s Kenma...someday.

“Stop calling me yours, I can hear you,” Kenma says, and Tetsurou lets loose a guffaw of unrestrained laughter.

“I didn’t do it out loud!” Tetsurou snorts.

“Stupid, Kuro,” Kenma mumbles and buries his head against Tetsurou’s shoulder. But just like before, Kenma’s inner thoughts betray him, going straight into Tetsurou’s mind as Kenma says. _I like it too much when *you* say it._

 _How about if I only think it? Is that okay?_ Tetsurou asks him mind-to-mind, the process a bit more clumsy since he is purposefully trying to communicate in this new, strange way.

The response Tetsurou gets is Kenma’s sharp, pointy fingers digging into the skin of Tetsurou’s back. A warning, but also there is a quietly mumbled, “Yes,” said against Tetsurou’s bare skin.

 

* * *

 

The two of them ultimately decide to not separate their magic. And later during this visit home, Tetsurou and Kenma discover that they can only communicate telepathically when in close proximity.  Telepathy requires physically connecting several thick threads of their shared magic, something they can only do within a few feet between them, or when they physically touch. It is definitely easiest when Tetsurou and Kenma touch.

When the full moon is over, the two of them return to the secluded beach south of Tokyo where they stashed their clothes, bags, and the train passes needed to return to the city.  Standing on the sand waiting for them are the two friends they traveled here with. They haven’t known Akaashi or Bokuto for long, but there is a bond beginning to form between the four young mermen.  

“You’re still blended!” Bokuto says far too loudly for the still, quiet air of this remote beach.  It seems to echo off the water like a proclamation of some sort. Tetsurou watches as Kenma’s face goes red with embarrassment.

“Bokuto-san, try to be a little more considerate of the things you say,” Akaashi says with a sigh.  

“But…” Bokuto mumbles, looking depressed after being admonished by his partner, “I was just really happy for them.”

Akaashi, being more subtle than Bokuto, asks Tetsurou, “Was this your choice? Or were they not able to separate you?”

“It’s by choice,” Tetsurou says with a sheepish grin.  He worries that he is overstepping by admitting this, but Kenma smiles as Tetsurou says it.  

The calm sound of Kenma’s voice says, _It’s okay,_ in Tetsurou’s mind.

“Hey, hey, hey!  See ‘Kaashi? I knew it was a good thing!  You should be more happy for your friends,” Bokuto says excitedly as he inflates with his normal happy energy at hearing the news.

Akaashi only responds with a long, suffering sigh, which immediately causes the four of them to break down into a fit of giggles.


	7. Traditions

**Notes for the Chapter:**

> In this chapter Kenma is 17 and Kuroo is 18, at the end of the chapter Kenma is almost 18 and Kuroo is almost 19.

Kenma sits next to Tetsurou in the locker room as they tie their shoes and prepare to head out onto the court. Tetsurou tries his best not to smile, but he fails when a strand of hair falls in front of Kenma’s face and Kenma swipes it back behind his ear. Tetsurou likes the length, and he even likes the way that Kenma is too lazy to dye the roots to match the rest of it.  It is a very Kenma thing to do.

 _You’re being creepy,_ Kenma says in Tetsurou’s head. _Stop staring at me like some lovesick fool._

 _But I am a lovesick fool,_ Tetsurou wordlessly answers back.

 _I promise to sic Bokuto on you if you don’t stop,_ Kenma threatens as he stands and walks out on the court.

“Hey, hey, hey!” a voice comes from the across the gymnasium. “Akaashi, look! Kenma and Kuroo came to get stomped. Isn’t that cute?”

“Oh no, I do believe that we owe you some hurt after you defeated us in the regional tournament,” Tetsurou says with a satisfied smirk. “I’ve been looking forward to it for weeks.”

Bokuto and Kuroo’s respective setters just sigh and shake their heads. “They are hopeless,” Akaashi says to Kenma from across the net.

“Completely,” Kenma agrees.

The four of them stop their banter to really warm up. For one of their teams, this will be the end of the spring interhigh tournament; and for either Bokuto or Kuroo, it will be the end of their high school volleyball career.

After an ample warm-up, a buzzer sounds to indicate a 60 second warning. The two teams gather and Tetsurou gives one of his famous odd pep-talks, but emotions are high and Nekoma knows this might be the last one they ever get from their captain, so they roll with it. Even Yaku doesn’t give Kuroo any crap. Similarly, Bokuto raises his voice high and energizes Fukurodani in a pre-game chant. From across the court, Tetsurou and Bokuto grin at each other and make teasing gestures indicating that the other is going down.  This game promises to be legendary.

 

* * *

 

And then it is summer and Bokuto and Tetsurou have both started college. Akaashi and Kenma are still finishing high school. The four of them are using the small overlap in their summer break schedules to hang out at the beach. It is weird to be so close to the ocean and their home, but to not actually go home. The day is nearing its end as the sun dips behind the hills to their backs. The sky is filled with the beautiful pinks and purples of dusk, until it finally settles into the deep blue of night.

It is a romantic kind of night, but Tetsurou knows he shouldn’t push his growing feelings onto Kenma. He is doing his best to respect Kenma’s desire to not move forward with any kind of partnering yet, even if Tetsurou does tease about being lovesick from time to time. Tetsurou tries hard to keep his emotions out of the magical link they share. Tetsurou knows it makes Kenma anxious to experience the feelings of love and attraction that he has accidentally let slip from time to time.

When the last of the other beach-goers leave, and Akaashi uses magic to keep them hidden from human sight, they strip off their clothing, hide it in an outcropping of rocks, and dive into the ocean. In a flicker of magic, each of them transforms into their merfolk forms. Bokuto does a flip completely out of the water as soon as he far enough from land and can gather enough speed. His shining silver scales reflect the moonlight as he slices easily back into the water. Akaashi also has a silver tail, but it is tipped with turquoise and yellow. He uses it to splash Bokuto with a warning.

“My magic is not perfect, try to keep from drawing attention. We are still very close to human habitations,” he says as Bokuto sputters from getting water into his air-breathing lungs.

Tetsurou and Kenma slowly drift on their backs on the surface. The summer-warmed current pushes through the water below them. It is a beautiful, clear night, and there are many stars starting to sparkle across the dark sky.

“I think I’m going to take the entrance exam for that technical college,” Kenma says. Tetsurou knows he means the one that has a game design program, and Tetsurou thinks that it is a good fit for his friend.

And that is what they are--friends. Though Bokuto and Akaashi have actually gone through the formal process their pod has for being promised, and all that entails, Kenma and Tetsurou are stuck somewhere between the closeness of friends and the intimacy of being promised. They are both still at the point of ‘maybe someday’ with one another, no matter how much Bokuto bugs them to make it official

Out of nowhere Bokuto zips under Tetsurou and pulls his friend under the water. Tetsurou comes up coughing a little. None of them are as quick at closing off their human lungs as they used to be. It actually feels weird to breathe using gills at this point.

“I think you should go and wrestle that idiot down to the ocean floor and smoosh his head into the sand,” Kenma tells Tetsurou with devious grin.

Kenma doesn’t have to tell Kuroo twice. The long, muscled form of Tetsurou’s merfolk body is made to be quick and explosive. He moves through the water at surprising speed until he almost catches up with Bokuto, who...isn’t alone. In front of them is Tetsurou’s father and grandfather, as well as Kenma’s mother, father, and sister.

Tetsurou gestures at all of them and then clicks a confused, _‘Why?’_

Bokuto waves his hands in an apologetic gesture. _“Sorry,”_ he clicks in response to Tetsurou’s confusion.

Tetsurou’s father points toward the surface and they all go up. Tetsurou tries his best not to fret, but there are only a few reasons why their families would be here, the most likely being that someone died or they came to bring Kenma and Tetsurou back home.

Tetsurou is the first to breach. He waits for the rest of them to surface, thoughts racing through his mind. He can feel the emotional turmoil he is pushing through the magical link with Kenma. Tetsurou tries to calm down until he knows what is actually happening, but the emotions build and flex and spill over into the thread of their magic that seems to always connect the two of them.

“It’s okay, Kuro,” Kenma says from behind him. “I asked them to come. Please calm down.”

The older merfolk surface along with Bokuto, while Akaashi bobs in the water next to Kenma. Tetsurou gives his friend a confused look until he feels the words and emotion Kenma shares through their magic.

_I love you, Kuroo Tetsurou. I love you, Kuro. I love you._

It is steady and sure and the strongest thing Tetsurou has ever felt through their connection.

_I want us to be promised to each other._

“Hey,” Bokuto interrupts,  “If you wanted to do this thing in your heads, Kenma, why’d you invite us?”

Bokuto follows that up with a soft ‘oof’ when Akaashi elbows him in the ribs.

Tetsurou knows that Kenma could never say the things he just telepathically admitted aloud.  Tetsurou never even imagined that Kenma's feelings might be that strong. Sure, there were fleeting moments where happiness flooded in, or a brief second of longing, sometimes a momentary attraction, but overwhelmingly it was their bond of friendship that stretched across the magic.

Tetsurou is shocked when Kenma looks up at him and speaks the words he shared in Tetsurou’s mind.  “I love you, Kuro. I want us to be promised to each other. Will you be my promised?”

Oh, Tetsurou thinks as he realizes that this really is happening.  Kenma is proposing partnership to him. Tetsurou finally allows the walls to fall. Tetsurou had carefully built them to keep his love for Kenma from escaping out into their magic, but now they are gone and the emotions are freed.  Kenma’s eyes go wide as he experiences the affection Tetsurou has for him. Tetsurou is surprised when an equally strong flood of emotion from Kenma reaches him. There is so much that it simply overwhelms them into silence, the two of them just allowing themselves to know the truth of how the other feels.  

 _I promise myself to you,_ Kenma says to Tetsurou.

 _And I promise myself to you,_ Tetsurou responds in kind as he reaches out and pulls Kenma into an embrace.  

Though embracing isn’t new to them, the slow press of Tetsurou’s lips to Kenma's lips is.  The kiss is gentle and Tetsurou can’t help but smile into it, laughing quietly against Kenma's mouth.

“So are they promised or not,” Bokuto asks, obviously confused as he cocks his head to the side and watches his friends kiss.

Akaashi places his hand atop Bokuto’s head and slowly pushes his partner down below the water’s surface, effectively silencing the chatty merman.

When Tetsurou and Kenma finally break the kiss, they continue with the traditions of their pod, as they introduce their partner to their family.

“Mother, father, sister--” Kenma begins, voice shaking, as he and Tetsurou come before Kenma’s family, “This is my beloved partner and mate.”

Tetsurou can’t believe that Kenma makes it through the traditional family greeting, though he is very red as Kenma’s family welcomes Tetsurou officially into their family.  

Then, Tetsurou turns to the two elder Kuroo’s and also says, “Father, grandfather--this is my beloved partner and mate,” which is quickly followed by warm welcomes from Tetsurou’s family.  

“This is just weird,” Bokuto says as he observes the customs of another pod.  “I could have never said that stuff to my grandpops about you, ‘Kaashi.”

They all laugh and Bokuto earns another elbow to the ribs.  Tetsurou smiles at his friend, because Bokuto knows just when to break the tension of a situation.  Tetsurou is positive that Bokuto is the only other merfolk that noticed how red Kenma had been, and how close Kenma was to panicking at the severity of the required cultural traditions.  Bokuto is, after all, just as good of a friend to Kenma as he is to Kuroo.

 _‘Thank you_ ,' Tetsurou clicks at Bokuto.  Bokuto just nods and affectionately drapes an arm around Akaashi’s shoulders.

 _I might not be ready for the mate bit,_ Tetsurou hears over the magic connection.

Tetsurou snorts and tries his best to not cause a scene over words that only he and Kenma can hear.

 _Yeah, that is probably a little fast. How about we stick to kissing for awhile,_ he says back, and he feels some of the tension melt away from Kenma.

 _Who would want to smooch your ugly mug, Kuro,_ Kenma asks teasingly.  

 _You,_ is the succinct and very correct answer with which Tetsurou replies.


End file.
